1. Field of the Invention
The present invention relates to a process of catalytic gasification of coal by using a highly active alkali metal or alkaline earth metal catalyst for coal gasification, loaded onto a coal, which catalyst is prepared by mixing an inexpensive, low rank coal, such as lignite, brown coal, subbituminous coal and the like, with an aqueous solution of an inexpensive salt such as NaCl, KCl and the like, as a starting material for the catalyst, and only the alkali metal or alkaline earth metal is introduced into the coal as the catalyst.
2. Description of the Prior Art
Coal gasificatiion techniques have been developed for a long time and utilized in the manufacture of synthetic gases and hydrogen gas. Recently, processes of catalytic coal gasification have been actively developed, which are directed to an increase in efficiency of gasification. The processes of catalytic coal gasification promote gasification reactions catalytically, wherein a catalytically active material fed into a gasification furnace together with a coal, is interposed between the coal and a gasifying agent.
There have been reported various substances, such as alkali metal salts, alkaline earth metal salts, VIII group transition metals, etc., which promote coal gasification reactions. Particularly, it has been known that alkali metal carbonates, such as K.sub.2 CO.sub.3, Na.sub.2 CO.sub.3 and the like, have a very prominent catalytic effect on steam gasification reactions. In C.C.G. processes that the EXXON group is developing, the steam gasification of coal is effected at 700.degree. C. using K.sub.2 CO.sub.3 as a catalyst. However, snce the K.sub.2 CO.sub.3 catalyst reacts with mineral matter in the coal, the complete recovery of the catalyst from reaction residues is substantially impossible. This would be a big problem from an economical point of view. Accordingly, attention has been paid to preparation of highly active gasification catalysts, using inexpensive materials for the catalysts.
Because of low prices and existence in large quantities, alkali chlorides such as NaCl, KCl and the like, therefore, may be preferable as materials for the catalysts. However, the use of these chlorides as a coal gasification catalyst presents two major problems. One is the inactivity of these chlorides for gasification reaction, and the other is corrosion of gasification apparatuses caused by hydrogen chloride generated from said chlorides. Therefore, it is necessary to activate the inactive chlorides to provide good gasification catalysts and further to remove chlorine in advance, so that an appropriate catalyst loading method to be used therefor has been required to be developed.